This invention pertains to means and methods for performing prolonged epidural anaesthesia. Epidural anesthesia is a delicate procedure in which the anaesthetist, after precisely locating the epidural space with a needle without encroaching on the dural structure or penetrating an epidural vein, inserts a catheter for the administration of an analgesic or anaesthetic for retention over a period of hours or days, depending on the patient's condition to be treated.
The presently available medical equipment and methods used in such procedures are discussed in "Handbook of Epidural Anaesthesia and Analgesia" published by Grune & Stratton, Inc., Orlando, Fla. 32887.
For other applications, "Fogarty" brand arterial embolectomy catheters, made by American Edwards Laboratories, provide a catheter with a balloon tip to be inflated for the purpose of removing emboli and thrombi from arteries. Shinnick U.S. Pat. No. 3,680,544 discloses a spinal syringe and needle, fitted with a catheter having an inflatable balloon at its tip. The instrument is designed for insertion through the wall of the heart into the right ventricular cavity. After insertion, the balloon is inflated to prevent displacement of the catheter. When the needle is withdrawn, the catheter remains in place for administering medication to the heart. Taylor U.S. Pat. No. 3,952,742 discloses a similar device for penetrating the wall of the heart and anchoring the tip of a catheter in place inside the heart by inflating a small balloon. Sheridan/CF.TM. tracheal tube has a pilot balloon whose purpose is to indicate the condition of a retention balloon inserted in a trachea to retain a tracheal tube.
The positioning of the catheter in the epidural space is very important in the epidural anaesthesia process to deliver the anesthetic to the area to be treated, to achieve the purpose of the epidural block. In this connection, excessive movement after positioning of the catheter also produces undesirable effects. Prior art catheter tubes have a high potential for displacement in the epidural space.
While performing epidural anaesthesia it is important not to puncture the dura which borders the epidural space on one side. One precautionary measure used to help prevent damage to the dura is to use a needle such as the standard Tuohy needle that directs the catheter away from the dural area. Even with the use of an appropriate needle, using a prior art epidural catheter can still readily cause damage to the dura because the flow of anaesthesia can be directed toward the dura.
Prior art catheter tubes have utilized narrow blue or black bands regularly spaced along the tube to indicate incremental lengths of tubing. These bands are often confusing and are difficult to read quickly.
Prior art epidural catheters extend from the patient to an external source of medication. They are prone to tangling and are awkward to handle during the insertion of the catheter.
Accordingly, an object of this invention is to provide a means for inserting a catheter in the epidura with minimal movement of the catheter after insertion.
Another object of this invention is to provide an epidural catheter that is easier to visually position.
Still another object of this invention is to provide an epidural catheter that is less likely to cause damage to the dura.
Yet still another object of this invention is to provide an epidural catheter that is less subject to tangling.
Other objects and advantages will become apparent by reference to the following description and drawings.